How the hell do I do this.....

[fairlady]

I am not a great fan of lunging although I appreciate it has its place.
However I use a lunge line a lot.......

I am trying to teach my two voice aids, which obviously I use
on a daily basis, however, they react instantly when I am beside them but
to try to get them to 'leave my side' seems to be impossible.

I had Bertie today on a lunge line, walking round the field, walk-on etc., but as soon as I dropped back a bit he would circle and run back to my side, I attempted to keep him circling at one point but he suddenly bolted back in and just stood as close to me as it was possible to stand. Sioned was very
similar yesterday, both are 120% happy to 'follow me' or walk beside me wherever I want to go but not so happy to 'go it alone'.

I don't want to tell them off because neither are being naughty, they just
don't understand WHY I want them to leave me. Bless its totally alien to them because until now I have made them be 'beside me' whilst
leading them. How can I do this
on my own.........do I need to get somebody in to stand by their Heads or
is there another way? I am trying to prepare them for long reining.....